203 



STRASBURGER'S NEW INVESTIGATIONS ON THE 

 PROCESS OF FERTILISATION IN 

 PHANEROGAMS. 



By THOMAS HICK, B.A., B.Sc, 

 Preside7it of the Botmiical Sectio7i of the Yorkshire Naturalists Unioji. 



(Continued from page 178.) 



The details of the fertilising process as given up to this point were 

 determined, as already intimated, for the most part in orchids. But 

 other monocotyledons exhibit similar phenomena, and hence the 

 account given may be taken as applicable to most plants of this class. 

 The difficulties attendant upon the investigation of the process in 

 Dicotyledons prevented a complete demonstration of all the details, 

 and our author, therefore, chiefly confined himself to a demonstra- 

 tion of the existence of the cell-nucleus in the pollen-tube up to the 

 point of its entrance into the micropyle, to finding on the other 

 side the fertilising sperm-nucleus in the oosphere or egg, and to 

 establishing in this sperm-nucleus a structure corresponding with 

 that of the generative cell-nucleus in the pollen-tube. In Mofiotropa 

 hypopitys he found it easy to see the pollen-tube enter the micropyle, 

 and could even follow it some distance within, in favourable material 

 prepared from flowers whose stamens were withering. The egg- 

 apparatus showed the same structure as in orchids, the synergidae 

 being provided at their apices with small, often distinctly-streaked 

 caps, and the three antipodal cells were easy of observation. In 

 Torenia asiatica, as is known, the embryo-sac grows forward free to 

 the micropyle of the ovule and displays the egg-apparatus, but the 

 cell-nuclei in the pollen-tube are small, and difficult to demonstrate. 

 For many demonstrations, nevertheless, Torenia is very valuable. 

 Nothing is easier than to establish that here the membrane at the 

 apex of the embryo-sac is broken through by the synergidae, and that 

 the caps of the synergidae are built up from the cytoplasma of the 

 same, and consequently are to be ascribed to them. The wall of the 

 embryo-sac over the caps is dissolved during the originating of these 

 caps, and takes no part in their formation. It can be easily and 

 certainly proved also that in Toi'enia the pollen-tube penetrates into 

 the egg-apparatus between the caps of the synergidae, its contents 

 remaining sharply limited from those of the synergidae. 



In the last section of his work, which constitutes more than one- 

 half of the whole, Strasburger proceeds to consider the nature of 

 generation or reproduction, in the light of the facts and observations 

 brought forward in the preceding sections. In his opinion, these 



April 1885. 



